Cloning and sequencing of Schizosaccharomyces pombe DNA topoisomerase I gene, and effect of gene disruption.

We cloned the structural gene topl+ for Schizosaccharomyces pombe DNA topoisomerase I (topo I) by hybridization. An eight-fold increase of topo I relaxing activity was obtained in S. pombe cells transformed with multicopy plasmid with topl+ insert. Nucleotide sequence determination showed a hypothetical coding frame interrupted by two short introns, encoding a 812 residue polypeptide (M.W. 94,000), 43 residues longer than and 47% homologous to Saccharomyces cerevisiae topo I. We show that the topl (null) strain made by gene disruption is viable, although its generation time is 20% longer than that of wild type. The topl locus is mapped in the long arm of chromosome II, using the Leu+ marker integrated with the cloned topl+ sequence. We constructed a double mutant topl (null) top2 (ts) and found its defective phenotype similar to that of previously obtained topl (heat sensitive) top2 (ts). The other double mutant topl (null) top2 (cs), however, was lethal. Our results suggest that topl+ gene of S. pombe is dispensable only if topo II activity is abundant.     

Clinical studies on cell-mediated immunity in patients with renal cell carcinoma: interleukin-2 and interferon-γ production of lymphocytes

Summary The authors examined interleukin-2 (IL-2) production and interferon (IFN) production of peripheral blood mononuclear cells in 28 patients with renal cell carcinoma and 17 control subjects. The peripheral blood was obtained prior to the initiation of therapeutic procedures. The patients were divided into two groups according to tumor size, 5 cm and >5 cm. The production of IL-2 and IFN was measured by immunoradiometric assay. As a result, in the patients with tumors >5 cm, IL-2 and IFN production was impaired. However, in the patients with tumors 5 cm, IFN production was enhanced, though IL-2 production was not significantly different from that of the control subjects. There was no significant correlation between IL-2 production and IFN production.     

The fission yeast cut1+ gene regulates spindle pole body duplication and has homology to the budding yeast ESP1 gene

Mutations in the fission yeast cut1+, cut2+, and cut10+ genes uncouple normally coordinated mitotic events and deregulate, rather than arrest, mitosis. DNA synthesis continues, making polyploid nuclei with several spindles. Multiple, aberrant spindle pole bodies (SPBs) are produced in cut1 mutant cells. The cut1+ and cut2+ genes are cloned by transformation. High gene dosage of cut1+ also complements cut2 and cut10 mutants. The cut2+ gene, however, complements only cut2. The 210 kd cut1+ gene product contains putative ATP binding and helical coil regions followed by a COOH-terminal domain homologous to the S. cerevisiae gene ESP1. Mutations in the ESP1 gene also result in many SPBs. The cut1+ product is shown by anti-cut1 antibody to be a rare component of the insoluble nuclear fraction. It may play a key role in coupling chromosome disjunction with other cell cycle events and is potentially a component, regulator, or motor for the SPB and/or kinetochores.     

Prostaglandin D2, a potential antineoplastic agent

Cytotoxic actions of various prostaglandins were examined on L1210 mouse leukemia and several human leukemia cell lines, and prostaglandin D₂ (PGD₂) was found most active. PGD₂ exerted a dose dependent inhibition of L1210 cell growth over 3.6 μ$\text{M}$. At 14.3 μ$\text{M}$ growth was completely inhibited, and the number of viable cells remarkably decreased during culture. Microscopically the remaining cells showed degenerative changes with many vacuoles in their cytoplasm. The IC₅₀ value of PGD₂ on L1210 cell growth was calculated to be 6.9 μ$\text{M}$ (2.4 μg/ml), and at this concentration the DNA synthesis in 24 hr cultured cells was also decreased to a half of the level in the control cells. Such growth inhibition by PGD₂ was also found at similar concentrations with several human leukemia cell lines such as NALL-1, RPMI-8226, RPMI-8402, and Sk-Ly-16. Among other prostaglandins tested, PGA₂ showed a comparable, and PGE₂ a less but significant growth inhibitory activity, while PGB₂, PGF_2α and PGI₂ had no such effects on cell proliferation at 14.3 μ$\text{M}$ concentration. These results suggest a potential antineoplastic activity of PGD₂.     

A new approach to determine the stereospecificity in lipase catalysed hydrolysis using circular dichroism (CD): lipases produce optically active diglycerides from achiral triglycerides

We describe a sensitive CD method for determining the stereospecificity in lipase (E.C.3.1.1.3) catalysed hydrolysis of triacyl glycerols into diacyl glycerols. The diglycerols were converted to chiral tert-butyldimethylsilylated 1,2- or 2,3-di-O-benzoyl-sn-glycerol (5 or 5'), and their CD was measured. This approach showed for the first time that lipases produce optically active diacyl glycerides from achiral tripalmitin and tribenzoyl glyceride with a variable extent of enantioselectivity depending on the acyl groups and the enzymes.     

The location of ribosomal cistrons (rDNA) in chromosomes of the rat

In situ hybridization of ³H-labelled ribosomal RNA to the chromosomes of rat bone marrow cells revealed that clusters of ribosomal cistrons (rDNA) are located in the secondary constrictions of chromosomes No. 3 and 12 and near the centromere of chromosome No. 11, both associated with the late DNA-replicating regions. They were not found in Nos. 1, 2, 13, 19, 20, and the Y chromosome.     

Lagrangian tracking measurements revealed the temporal dynamics of nitrogen and phosphorus spiralling in a large Japanese river

Limnology - The in-stream processing of nutrients plays an important role in the fluvial nutrient transport from lands to the ocean, but few empirical studies have addressed the temporal dynamics...     

A 3D-Video-Based Computerized Analysis of Social and Sexual Interactions in Rats

A large number of studies have analyzed social and sexual interactions between rodents in relation to neural activity. Computerized video analysis has been successfully used to detect numerous behaviors quickly and objectively; however, to date only 2D video recording has been used, which cannot determine the 3D locations of animals and encounters difficulties in tracking animals when they are overlapping, e.g., when mounting. To overcome these limitations, we developed a novel 3D video analysis system for examining social and sexual interactions in rats. A 3D image was reconstructed by integrating images captured by multiple depth cameras at different viewpoints. The 3D positions of body parts of the rats were then estimated by fitting skeleton models of the rats to the 3D images using a physics-based fitting algorithm, and various behaviors were recognized based on the spatio-temporal patterns of the 3D movements of the body parts. Comparisons between the data collected by the 3D system and those by visual inspection indicated that this system could precisely estimate the 3D positions of body parts for 2 rats during social and sexual interactions with few manual interventions, and could compute the traces of the 2 animals even during mounting. We then analyzed the effects of AM-251 (a cannabinoid CB1 receptor antagonist) on male rat sexual behavior, and found that AM-251 decreased movements and trunk height before sexual behavior, but increased the duration of head-head contact during sexual behavior. These results demonstrate that the use of this 3D system in behavioral studies could open the door to new approaches for investigating the neuroscience of social and sexual behavior.